1. Field of the Invention
The invention relates to the field of printing systems, and in particular, to processing JDF job tickets in a printing system to re-define printing commands in a printing file.
2. Discussion of Related Art
Printing systems generally include a localized print controller that connects to one or more host systems. The print controller controls the overall operation of the printing system including, for example, host interfacing, interpretation or rendering, and lower level process control or interface features of the print engines of the printing system. Host interaction may include appropriate adapters for coupling the printing system to one or more host systems that transmit printable files to the printing system. The printable files (also referred to as print data files or content files, among other designations) are generally encoded in the form of a page description language (PDL), such as PostScript (PS), Portable Document Format (PDF), Printer Command Language (PCL), etc.
In whatever form the printable files may be encoded or formatted, the print controller within the printing system interprets or renders the file to generate sheetside bitmaps of the file. For example, the printable file may include page descriptions for each logical page of the file that are written in a particular PDL. The print controller may then interpret the page descriptions for each page to generate the sheetside bitmaps for the file. The sheetside bitmaps represent the images to be printed on one side of a sheet of paper by a print engine. The print controller stores or buffers the sheetside bitmaps in accordance with storage capabilities of the particular print controller. The print controller then forwards the sheetside bitmaps to one or more print engines (also referred to as an imaging engine or as a marking engine) for printing.
In conventional printing systems, when the host system is instructed to print a particular file comprised of textual and graphical content, the host system converts the file into a printable file in one of a variety of PDLs. The host system also includes printing parameters (also referred to as device control commands or instructions) with the printable file.
One way of describing the printing parameters for a print job is through creation of a job ticket. A job ticket defines a print job and associates one or more printable files with information that defines various printing parameters for actual physical printing of the printable files. Among other things, a job ticket may include layout parameters indicative of where each logical page defined by the PDL of the printable files is to be placed on a sheet side of the printable medium. One common standard for defining a job ticket is the Job Definition Format (JDF). The JDF job ticket, as presently defined for JDF by the CIP4 Organization, which is known to those skilled in the art, is written in Extensible Markup Language (XML) format. In conventional printing systems, processing of JDF job tickets is performed in the host system. In response to receiving or identifying a JDF job ticket, the host system processes the JDF job ticket to identify the printing parameters for a print job. The host system then generates a printable file in the appropriate PDL that includes the content intended for printing and also includes the printing parameters defined in the job ticket to modify or adjust the actual printed output. This can cause problems as it may overload the host system in processing the JDF job ticket and generating the printable files, as the printable files with the included printing parameters can get quite large. Also, if a network connection is used between the host system and the printing system, then the large printable files may congest the network or unnecessarily use up network resources.
To alleviate such problems, co-owned and co-pending U.S. patent application Ser. No. 12/118,191, filed May 9, 2008 (hereinafter U.S. application Ser. No. 12/118,191), teaches a printing system that processes job tickets in the printing system instead of a host system. Thus, the host system may transmit a job ticket and a printable file to the printing system for processing, instead of processing the job ticket locally on the host system. The print controller in the printing system then processes the job ticket to identify the printing parameters defined in the job ticket, and controls printing of the printable file based on the identified printing parameters. The processing of job tickets is advantageously moved from the host system to the printing system, which relieves the processing responsibility from the host system and avoids transmitting large files over a network.
In the field of production printing, print jobs often consist of a printable file and a job ticket, as described above. In particular, the layout and imposition parameters of the job ticket may define a new placement, size and orientation for the printed pages that is different from what is described in the PDL printable file. On the other hand, the layout parameters for each logical page of the printable file may be substantially identical. In a printing system as in U.S. application Ser. No. 12/118,191, in which a print controller process both the printable file and the job ticket, the printing system may open the original printable file, seek to the first logical page, execute its instructions, then switch to the job ticket to execute printing instructions in accordance with the new layout parameters, then return to the printable file, seek to the second page, execute its instructions, switch again to the job ticket file to execute substantially identical layout instructions, and so on. Use of a printing system in which the printer receives and parses a job ticket reduces the burden on the host system, but the repeated processing of the layout parameters within the job ticket for each logical page of the printable file is time-consuming. Thus, improved techniques are needed to efficiently process a job ticket as regards layout parameters when processing a job ticket within a printing system.